1. Field of the Invention
This invention relates to a polycarbonate composition, more particularly to a polycarbonate composition which is suitable for forming into a heat shielding material and which includes a terminal hydroxyl-containing polycarbonate and a halogen-containing alkali metal tungsten oxide.
2. Description of the Related Art
In recent years, as awareness of environmental protection increases, how to save an energy source has become an important issue. The use of a heat shielding material is one of the methods for saving the energy source, and may provide a shelter from sunshine and inhibit the temperature rise. Furthermore, the use of an air condition may be decreased. Therefore, the heat shielding material has become a good tool for saving the energy source.
JP 2008-214596 discloses a polycarbonate composition and a heat shielding material made from the same. The polycarbonate composition includes 100 parts by weight of terminal hydroxyl-containing polycarbonate and 0.001 to 5 parts by weight of tungsten oxide. The tungsten oxide is represented by Formula (a) as follows:MaWbOc  (a)
where M represents hydrogen, helium, alkaline earth metals, alkali metals, rare-earth metals, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Hf, Os, Bi, or I; W represents tungsten; 0.001≦a/b≦1; and 2.2≦a/b≦3.
Embodiments of JP 2008-214596 disclose the use of 0.15 part by weight and 0.24 part by weight of the tungsten oxide, and a sum of a visible light transmittance and an infrared shielding ratio of the heat shielding material made therefrom ranges from 134% to 136%, and a haze value of the heat shielding material ranges from 0.9% to 2.4%. Although the sum of the visible light transmittance and the infrared shielding ratio of the heat shielding material in JP 2008-214596 ranges from 134% to 136%, the infrared shielding ratio of the heat shielding material added with 0.24 part by weight of the tungsten oxide is increased to 76.2%, which still could not meet industrial requirements.